Browsing by Author "Ohijeagbon, I.O."
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Item Rapid cyclic heating of mild steel and its effect on microstructure and mechanical properties(IOP Conference series: Materials Science and Engineering, 2018) Aweda, J.O.; Orhadahwe, T.A; Ohijeagbon, I.O.The effect of subjecting mild steel to several cycles of rapid heat treatment on its mechanical properties and microstructure was investigated. Mild steel of 0.213 wt % carbon was subjected to transformation heat treatment from austenite to pearlite and quenched in running water. Rapid heating was achieved by preheating an electric muffle furnace to 840 oC before charging the samples into it. Each cyclic heat treatment was for a period of 200 seconds held at 840 oC. and cooled to 700 0C which was repeated four times. The effects of cycle numbers were evaluated by testing for impact, hardness, ultimate tensile strength and microstructural properties. The results showed that after 4th cycle of rapid heating the samples had impact energy 64.6 J, Brinell hardness number 563 and ultimate tensile strength 1257.78 N/mm. The samples after one cycle had ultimate tensile strength 1027.45 N/mm 10.396% and impact energy 286.174 N.m before failure. Through cyclic heating, grain refinement was achieved by the fast-simultaneous nucleation at the grain boundaries and the fast martensite to austenite transformation due to the fast heating rate which prevented austenite grain growth. Mechanical properties of the studied steel sample were improved with the rapid heat treatment cycles given.Item Suitability of pulverized cow bones as a paving tile constituent(IOP Conference series: Materials Science and Engineering, 2018) Aweda, J.O.; Omoniyi, P.O.; Ohijeagbon, I.O.Economic advantage of waste has been clamoured severally in order to improve the environment and reduce pollution. In Nigeria, the common materials used for the production of paving tiles are granite dust and cement, in some cases silica sand is added. This study is aimed at investigating the feasibility of using available raw materials such as laterite, silica sand and pulverized cow bones to develop paving tiles. Tiles of 200 mm × 100 mm × 60 mm were produced and the effects of various materials added were investigated and analysed. The production method employed was casting and curing was done for twenty-eight (28) days. Physical and mechanical analyses of the paving tiles showed that the tiles with mixing ratio of 4:1:3 (laterite: pulverized cow bones: silica sand) with 20% cement stabilization was the optimum mix ratio, producing the maximum compressive strength and modulus of rupture of 5.05 MPa and 1.83 MPa respectively